1. Field of the Invention
This invention generally relates to a soft serve ice cream dispensing apparatus and more particularly to a system for recirculating ice cream to prevent liquefaction adjacent the dispensing valve.
2. Description of the Prior Art
Soft serve ice cream dispensing apparatus are generally known in the art. Examples of such apparatus are disclosed in U.S. Pat. Nos. 2,784,565 and 3,050,960. Such apparatus generally consist of a horizontal cylindrical tank surrounded by a refrigerant chamber. The tank is open on one end and closed by a closure plate containing a dispensing valve. The closure plate, generally made from a nylon or other suitable polymeric material, is subject to ambient temperature. Even though nylon is a fairly good heat insulator, some heat nonetheless is absorbed from the ambient air causing the ice cream to liquefy in the area adjacent the dispensing valve.
Liquefaction of the ice cream is a highly undesirable condition. In such a case, the liquid must be drawn off and discarded before the ice cream is served causing a considerable amount of waste. Furthermore, depending upon the amount of time since the last customer was served, the liquid ice cream can become subject to bacterial buildup and thus require that the entire machine be cleaned and sanitized.
Various means are known in the art for reducing liquefaction of the ice cream in the area adjacent the dispensing valve. For example, in U.S. Pat. No. 2,784,565 to Stalkup, a recirculation loop is provided external to the tank. The recirculation loop is attached between the dispensing valve chamber and the tank. When the dispensing valve is closed soft serve ice cream is continuously recirculated through the dispensing valve chamber and back into the tank.
U.S. Pat. No. 3,050,960 to Clifford discloses a soft serve ice cream machine with an internal recirculation loop. More specifically, a hollow shaft is provided interior to the tank. One end of the shaft is in open communication with the dispensing valve chamber while the opposite end contains an exit orifice to allow the ice cream to be recirculated back into the tank. Another passageway is provided in communication with the inside of the tank and the dispensing valve chamber to allow the ice cream to flow from the tank into the dispensing valve chamber and into the hollow shaft.
In both of the aforementioned machines, the dispensing valve chamber forms a portion of the recirculation loop. Since the dispensing valve chamber is the area where the greatest amount of heat is absorbed from the ambient air, the ice cream that is recirculated through the dispensing valve chamber can cause additional loading of the refrigeration system.
Another problem with the recirculation systems disclosed in the prior art is that such systems are relatively difficult to clean. More specifically in both the Clifford and Stalkup patents the recirculation loop includes a hollow recirculation pipe that extends substantially the length of the horizontal tank that is cumbersome to clean. In addition, the Clifford patent discloses a second flow passageway between the tank and the valve dispensing chamber which must also be cleaned.